<!doctype html>
<html lang="en">
<head>
 <meta charset="UTF-8" />
 <title>Document</title>
 <style type="text/css">
  #c{
   margin: 0 auto;
   display: block;
  }
  #r{
   display: block;
   margin: 0 auto;
  }
  #r::before{
   color: black;
   content: attr(min);
   padding-right: 10px;
  }
  #r::after{
   color: black;
   content: attr(max);
   padding-left: 10px;
  }  
 </style>
</head>
<body>
 <canvas id="c"></canvas>
 <input type="range" id="r" min="0" max="100" step="1">
 
 <script type="text/javascript">
  var canvas = document.getElementById('c');
  var ctx = canvas.getContext('2d');
  var range = document.getElementById('r');
 
  //range控件信息
  var rangeValue = range.value;
  var nowRange = 0; //用于做一个临时的range
 
  //画布属性
  var mW = canvas.width = 250;
  var mH = canvas.height = 250;
  var lineWidth = 2;
 
  //圆属性
  var r = mH / 2; //圆心
  var cR = r - 16 * lineWidth; //圆半径
 
  //Sin 曲线属性
  var sX = 0;
  var sY = mH / 2;
  var axisLength = mW; //轴长
  var waveWidth = 0.015 ; //波浪宽度,数越小越宽 
  var waveHeight = 6; //波浪高度,数越大越高
  var speed = 0.09; //波浪速度，数越大速度越快
  var xOffset = 0; //波浪x偏移量
 
  ctx.lineWidth = lineWidth;
 
  //画圈函数
  var IsdrawCircled = false;
  var drawCircle = function(){
 
   ctx.beginPath();
   ctx.strokeStyle = '#1080d0';
   ctx.arc(r, r, cR+5, 0, 2 * Math.PI);
   ctx.stroke();
   ctx.beginPath();
   ctx.arc(r, r, cR, 0, 2 * Math.PI);
   ctx.clip();
 
  }
 
  //画sin 曲线函数
  var drawSin = function(xOffset){
   ctx.save();
 
   var points=[]; //用于存放绘制Sin曲线的点
 
   ctx.beginPath();
   //在整个轴长上取点
   for(var x = sX; x < sX + axisLength; x += 20 / axisLength){
    //此处坐标(x,y)的取点，依靠公式 “振幅高*sin(x*振幅宽 + 振幅偏移量)”
    var y = -Math.sin((sX + x) * waveWidth + xOffset);
 
    var dY = mH * (1 - nowRange / 100 );
 
    points.push([x, dY + y * waveHeight]);
    ctx.lineTo(x, dY + y * waveHeight);  
   }
 
   //封闭路径
   ctx.lineTo(axisLength, mH);
   ctx.lineTo(sX, mH);
   ctx.lineTo(points[0][0],points[0][1]);
   ctx.fillStyle = '#1c86d1';
   ctx.fill();
 
   ctx.restore();
  };
 
  //写百分比文本函数
  var drawText = function(){
   ctx.save();
 
   var size = 0.4*cR;
   ctx.font = size + 'px Microsoft Yahei';
   ctx.textAlign = 'center';
   ctx.fillStyle = "rgba(06, 85, 128, 0.8)";
   ctx.fillText(~~nowRange + '%', r, r + size / 2);
 
   ctx.restore();
  };
 
  var render = function(){
   ctx.clearRect(0, 0, mW, mH);
 
   rangeValue = range.value;
 
   if(IsdrawCircled == false){
    drawCircle(); 
   }
 
   if(nowRange <= rangeValue){
    var tmp = 1;
    nowRange += tmp;
   }
 
   if(nowRange > rangeValue){
    var tmp = 1;
    nowRange -= tmp;
   }
 
   drawSin(xOffset);
   drawText(); 
 
   xOffset += speed;
   requestAnimationFrame(render);
  }
 
  render();  
 </script>
</body>
</html>
